Transcriptional Dysregulation Underlies Both Monogenic Arrhythmia Syndrome and Common Modifiers of Cardiac Repolarization

• DOI: 10.1161/circulationaha.122.062193
• Publication Date: 2022-12-16T10:00:32Z
• Authors: Kevin R. Bersell; Tao Yang; Jonathan D. Mosley; Andrew M. Glazer; Andrew T. Hale; Dmytro O. Kryshtal; Kyungsoo Kim; Jeffrey D. Steimle; Jonathan D. Brown; Joe-Elie Salem; Courtney C. Campbell; Charles C. Hong; Quinn S. Wells; Amanda N. Johnson; Laura Short; Marcia A. Blair; Elijah R. Behr; Evmorfia Petropoulou; Yalda Jamshidi; Mark D. Benson; Michelle J. Keyes; Debby Ngo; Ramachandran S. V...; Qiong Yang; Robert E. Gerszten; Christian Shaffer; Shan Parikh; Quanhu Sheng; Prince J. Kannank...; Ivan P. Moskowitz; John D. York; Thomas J. Wang; Bjorn C. Knollmann; Dan M. Roden
• Keywords: 0301 basic medicine; Sodium; Arrhythmias, Cardiac; NAV1.5 Voltage-Gated Sodium Channel; 3. Good health; [SDV] Life Sciences [q-bio]; Mice; Phosphatidylinositol 3-Kinases; 03 medical and health sciences; Phenotype; Humans; Animals; Myocytes, Cardiac; Receptors, Platelet-Derived Growth Factor; Brugada Syndrome

Background:

Brugada syndrome (BrS) is an inherited arrhythmia syndrome caused by loss-of-function variants in the cardiac sodium channel gene SCN5A (sodium voltage-gated channel alpha subunit 5) in ≈20% of subjects. We identified a family with 4 individuals diagnosed with BrS harboring the rare G145R missense variant in the cardiac transcription factor TBX5 (T-box transcription factor 5) and no SCN5A variant.

Methods: We generated induced pluripotent stem cells (iPSCs) from 2 members of a family carrying TBX5-G145R and diagnosed with Brugada syndrome. After differentiation to iPSC-derived cardiomyocytes (iPSC-CMs), electrophysiologic characteristics were assessed by voltage- and current-clamp experiments (n=9 to 21 cells per group) and transcriptional differences by RNA sequencing (n=3 samples per group), and compared with iPSC-CMs in which G145R was corrected by CRISPR/Cas9 approaches. The role of platelet-derived growth factor (PDGF)/phosphoinositide 3-kinase (PI3K) pathway was elucidated by small molecule perturbation. The rate-corrected QT (QTc) interval association with serum PDGF was tested in the Framingham Heart Study cohort (n=1893 individuals).

Results:

TBX5-G145R reduced transcriptional activity and caused multiple electrophysiologic abnormalities, including decreased peak and enhanced “late” cardiac sodium current (I Na ), which were entirely corrected by editing G145R to wild-type. Transcriptional profiling and functional assays in genome-unedited and -edited iPSC-CMs showed direct SCN5A down-regulation caused decreased peak I Na , and that reduced PDGF receptor ( PDGFRA [platelet-derived growth factor receptor α]) expression and blunted signal transduction to PI3K was implicated in enhanced late I Na . Tbx5 regulation of the PDGF axis increased arrhythmia risk due to disruption of PDGF signaling and was conserved in murine model systems. PDGF receptor blockade markedly prolonged normal iPSC-CM action potentials and plasma levels of PDGF in the Framingham Heart Study were inversely correlated with the QTc interval ( P <0.001).

Conclusions:

These results not only establish decreased SCN5A transcription by the TBX5 variant as a cause of BrS, but also reveal a new general transcriptional mechanism of arrhythmogenesis of enhanced late sodium current caused by reduced PDGF receptor–mediated PI3K signaling.